1. Field of the invention
The invention relates to sodium bicarbonate having a specific morphology and to a process for obtaining it.
There are various known processes for obtaining sodium bicarbonate.
A first process, generally termed the ammonia process and commonly used in industry, consists in treating an ammoniacal brine with a gas containing carbon dioxide (TE-PANG HOU-"Manufacture of soda"-2nd edition-American Chemical Society Monograph Series-1969-Hafner Publishing Company-pages 132 to 157).
Another process consists in mixing a saturated aqueous solution of sodium chloride with a nitrogenous organic base insoluble in water (generally an amine) and in treating the resulting mixture with a gas containing carbon dioxide (Pat. Nos. FR-A-2,545,079 and FR-A-2,551,428-SOLVAY & Cie).
To produce sodium bicarbonate of high purity, intended in particular for foodstuffs, an aqueous solution of sodium carbonate is subjected to the action of a gas containing carbon dioxide (SHREVE-"The Chemical Process Industries"-2nd edition-1956-McGraw-Hill Book Company, Inc.-page295).
In these known processes the treatment with the gas containing carbon dioxide produces an aqueous suspension of crystals of sodium bicarbonate. These processes accordingly involve a filtration of the suspension in order to extract the sodium bicarbonate crystals therefrom and a drying of these crystals. These two operations are prolonged and costly and moreover involve heavy investments. The sodium bicarbonate obtained after drying is generally in the form of a fine powder, the particles of which are of irregular shape and size and frequently have a wide particle size distribution.